Arthoplasty revision system and method

ABSTRACT

The present method includes the following steps: removing a portion of a previously implanted spinal arthroplasty device; and attaching a revision component to a remaining portion of the previously implanted spinal arthroplasty device to alter a biomechanical characteristic of the implanted arthroplasty device. Another aspect of the invention provides a method of limiting motion between adjacent vertebrae including the steps of accessing an implanted spinal arthroplasty device comprising a cephalad component fixed to a first vertebra and a caudal component fixed to a second vertebra inferior to the first vertebra, the cephalad and caudal components having a range of motion between them, and attaching a revision component to the cephalad and caudal components to reduce the range of motion. The invention also includes revision devices for revising the biomechanics of implanted spinal arthroplasty devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/033,082, filed Feb. 23, 2011, which is a continuationapplication of U.S. patent application Ser. No. 11/642,417, filed Dec.20, 2006, now issued as U.S. Pat. No. 7,914,556, which is acontinuation-in-part of commonly assigned U.S. patent application Ser.No. 11/206,676, filed Aug. 17, 2005, which is a continuation-in-part ofcommonly assigned U.S. patent application Ser. No. 11/071,541, filedMar. 2, 2005, now issued as U.S. Pat. No. 7,674,293. U.S. patentapplication Ser. No. 11/642,417 claims the benefit of U.S. ProvisionalApplication 60/752,277, filed Dec. 20, 2005 and U.S. ProvisionalApplication 60/847,013, filed Sep. 25, 2005. All of the references citedherein are hereby incorporated by reference in their entireties.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to devices and surgical methodsfor treatment of various spinal pathologies. More specifically, thepresent invention is directed to configurable and anatomically adaptableimplantable devices for use in a spine and surgical procedures foraltering the biomechanics of a spine, either temporarily or permanently.The devices alter, replace and/or revise existing anatomy and/orpreviously implanted devices.

BACKGROUND OF THE INVENTION

Back pain, particularly in the small of the back, or lumbosacral region(L4-S1) of the spine, is a common ailment. In many cases, the painseverely limits a person's functional ability and quality of life. Backpain interferes with work, routine daily activities, and recreation. Itis estimated that Americans spend $50 billion each year on low back painalone. It is the most common cause of job-related disability and aleading contributor to missed work.

Through disease or injury, the laminae, spinous process, articularprocesses, facets and/or facet capsules of one or more vertebral bodiesalong with one or more intervertebral discs can become damaged, whichcan result in a loss of proper alignment or loss of proper articulationof the vertebra. This damage can also result in an anatomical change,loss of mobility, and pain or discomfort. For example, the vertebralfacet joints can be damaged by traumatic injury or as a result ofdisease. Diseases damaging the spine and/or facets includeosteoarthritis where the cartilage of joints is gradually worn away andthe adjacent bone is remodeled, ankylosing spondylolysis (or rheumatoidarthritis) of the spine which can lead to spinal rigidity, anddegenerative spondylolisthesis which results in a forward displacementof the lumbar vertebra on the sacrum. Damage to facet joints of thevertebral body often results in pressure on nerves, commonly referred toas “pinched” nerves, or nerve compression or impingement. The result ispain, misaligned anatomy, a change in biomechanics and a correspondingloss of mobility. Pressure on nerves can also occur without facet jointpathology, e.g., as a result of a herniated disc.

One conventional treatment of facet joint pathology is spinestabilization, also known as intervertebral stabilization.Intervertebral stabilization desirably controls, prevents or limitsrelative motion between the vertebrae through the use of spinalhardware, removal of some or all of the intervertebral disc, fixation ofthe facet joints, bone graft/osteo-inductive/osteo-conductive materialpositioned between the vertebral bodies (with or without concurrentinsertion of fusion cages), and/or some combination thereof, resultingin the fixation of (or limiting the motion of) any number of adjacentvertebrae to stabilize and prevent/limit/control relative movementbetween those treated vertebrae.

Although spine fusion surgery is an efficacious treatment, complicationscan nonetheless result. Patients undergoing spine surgery frequentlycontinue to experience symptoms. For surgical procedures in the lumbarspine, failure rates as high as 37% have been reported after lumbarfusion and 30% for surgery without fusion. See Eichholz, et al.,“Complications of Revision Spinal Surgery,” Neurosurg Focus 15(3):1-4(2003). Post-operative problems can include decompression relatedproblems, and fusion related problems. Decompression related problems(i.e., loss of normal spine balance resulting in the head and trunk nolonger being centered over the pelvis) include, for example, recurrentdisc herniation, spinal stenosis, chronic nerve injury, infection, anddecompression. Fusion related problems can include, pain from the boneharvest site, failure of a fusion to develop, loosening of the implanteddevices, nerve irritation caused by the devices, infection, and pooralignment of the spine.

Stabilization of vertebral bodies can also be achieved (to varyingdegrees) from a wide variety of procedures, including the insertion ofmotion limiting devices (such as intervertebral spacers, artificialligaments and/or dynamic stabilization devices), devices promotingarthrodesis (rod and screw systems, cables, fusion cages, etc.), andcomplete removal of some or all of a vertebral body from the spinalcolumn (which may be due to extensive bone damage and/or tumorous growthinside the bone) and insertion of a vertebral body replacement(generally anchored into the adjacent upper and lower vertebral bodies).Various devices are known for fixing the spine and/or sacral boneadjacent the vertebra, as well as attaching devices used for fixation,including devices disclosed in: U.S. Pat. Nos. 6,585,769; 6,290,703;5,782,833; 5,738,585; 6,547,790; 6,638,321; 6,520,963; 6,074,391;5,569,247; 5,891,145; 6,090,111; 6,451,021; 5,683,392; 5,863,293;5,964,760; 6,010,503; 6,019,759; 6,540,749; 6,077,262; 6,248,105;6,524,315; 5,797,911; 5,879,350; 5,885,285; 5,643,263; 6,565,565;5,725,527; 6,471,705; 6,554,843; 5,575,792; 5,688,274; 5,690,630;6,022,350; 4,805,602; 5,474,555; 4,611,581; 5,129,900; 5,741,255;6,132,430; and U.S. Patent Publication No. 2002/0120272.

More recently, various treatments have been proposed and developed asalternatives to spinal fusion. Many of these treatments seek to restore(and/or maintain) some, or all, of the natural motion of the treatedspinal unit, and can include intervertebral disc replacement, nucleusreplacement, facet joint resurfacing, and facet joint replacement. Suchsolutions typically include devices that do not substantially impairspinal movement. See, U.S. Pat. Nos. 6,610,091; 6,811,567; 6,902,580;5,571,171; and Re 36,758; and PCT Publication Nos. WO 01/158563, WO2004/103228, WO 2005/009301, and WO 2004/103227. Thus, spinalarthroplasty has become an acceptable alternative to fusion,particularly in cases of degenerative disc disease. Arthroplasty devicescan be particularly useful because the devices are designed to create anartificial joint or restore the functional integrity and power of ajoint

SUMMARY OF THE INVENTION

It may be necessary to alter or revise an implanted spinal prosthesis orfusion device. For example, due to the continued progress of spinedisease, a spine surgeon may need to remove part or all of a previouslyimplanted arthroplasty device in order to provide access to thepatient's vertebra(e) and/or disc. After performing a surgical procedureon the patient (e.g., implantation of an artificial disc, resection ofthe lamina, etc.), the surgeon may want to provide the patient with aprosthesis to replace the function of the original device or to performan entirely new function. It would be desirable to use a remainingportion of the implanted arthroplasty device as part of the newprosthesis.

In another example, even if no portion of an implanted device isremoved, it may be desirable to revise the biomechanical function of theimplanted device. For example, an implanted arthroplasty device maypermit movement between the adjacent vertebrae to which it is attached.It may be desirable to change, limit or completely eliminate the motionbetween the cephalad and caudal portions of the prosthesis, therebychanging, limiting or eliminating movement between the vertebrae,without removal, or with only partial removal, of the existing implant.It would therefore be desirable to add a revision device to thearthroplasty implant to change the implant's biomechanics.

One aspect of the invention provides a method of revising an implantedarthroplasty device, such as an implanted arthroplasty device having acephalad component fixed to a first vertebra and a caudal componentfixed to a second vertebra inferior to the first vertebra. The methodincludes the following steps: removing a portion of a previouslyimplanted spinal arthroplasty device; and attaching a revision componentto a remaining portion of the previously implanted spinal arthroplastydevice to alter a biomechanical characteristic of the implantedarthroplasty device. In some embodiments, wherein the caudal componentincludes a caudal cup, the removing step includes the step of removingthe caudal cup from a fixation element. The attaching step may alsoinclude the step of attaching an attachment device to the caudal cupfixation element.

In some embodiments, wherein the cephalad component includes a cephaladarm and a cephalad bearing element, the removing step includes the stepof removing the cephalad bearing element from the cephalad arm. Theattaching step may also include the step of attaching a connectorhousing to the cephalad arm and attaching the connector housing to another arthroplasty element (such as the caudal component) or revisioncomponent. The removing step may also include the step of removing acaudal cup from a caudal fixation element, with the attaching stepincluding the step of attaching a caudal attachment device to the caudalfixation element and attaching the housing to the caudal attachmentdevice. In situations in which the cephalad component has two cephaladarms, the attaching step may include the step of attaching a crossbar tothe two cephalad arms.

In embodiments in which the cephalad component has an implanted cephaladarm, the removing step may include the step of removing a portion of theimplanted cephalad arm. The attaching step may also include the step ofattaching a new cephalad arm to a remaining portion of the implantedcephalad arm, such as by attaching a connector housing to the newcephalad arm and attaching the connector housing to an otherarthroplasty device element (such as the caudal component) or a revisioncomponent. The new cephalad arm may be located medial to or lateral tothe implanted cephalad arm. The removing step further may also includethe step of removing a caudal cup from a caudal fixation element, withthe attaching step including the step of attaching a caudal attachmentdevice to the caudal fixation element and attaching the housing to thecaudal attachment device. In situations in which the cephalad componenthas two implanted cephalad arms, the removing step may include the stepof removing a portion of each implanted cephalad arm and the attachingstep may includes the steps of attaching a new cephalad arm to aremaining portion of each implanted cephalad arm and attaching acrossbar to the two new cephalad arms.

Another aspect of the invention provides a method of altering thebiomechanics between first and second vertebrae including the steps ofaccessing an implanted spinal device (such as, e.g., a spinalarthroplasty device, a facet joint replacement device, a dynamicstabilization device, in interspinous space, and/or an artificial disc)comprising a cephalad component fixed to the first vertebra and a caudalcomponent fixed to the second vertebra inferior to the first vertebra,the cephalad and caudal components having a biomechanical relationship(such as, e.g., a range of motion) between them, and attaching arevision component to the cephalad and caudal components to alter thebiomechanical relationship (e.g., by reducing the range of motion). Insome embodiments, the attaching step substantially eliminates motionbetween the cephalad and caudal components. In embodiments in which thecephalad component has a cephalad bearing element and the caudalcomponent has a caudal bearing element, the attaching step may includethe step of attaching a revision component extending from one side ofthe cephalad bearing element to an opposing side of the caudal bearingelement. In embodiments in which the cephalad component further includesa cephalad arm, the attaching step may also include the step ofattaching the revision component to the cephalad arm.

Yet another aspect of the invention provides a revision device for animplanted spinal arthroplasty device, where the implanted spinalarthroplasty device has a cephalad component fixed to a first vertebraand a caudal component fixed to a second vertebra inferior to the firstvertebra. The revision device according to this aspect of the inventionhas an attachment component adapted to attach to a remaining portion ofan arthroplasty device component after a portion of the arthroplastydevice has been removed to alter a biomechanical characteristic of thearthroplasty device. In some embodiments in which the caudal componentof the implanted arthroplasty device has a caudal cup, the revisiondevice has a caudal attachment device adapted to be attached to a caudalcup fixation element after the caudal cup has been removed.

In embodiments in which the cephalad component of the implantedarthroplasty device has a cephalad arm, the revision device may have aconnector housing adapted to be attached to the cephalad arm and to another arthroplasty device element (such as the caudal component) or arevision component. In some embodiments, the revision device alsoincludes a caudal attachment device adapted to be attached to a caudalcup fixation element after the caudal cup has been removed, theconnector housing being adapted to be attached to the caudal attachmentdevice. In some embodiments, the revision device has a cross-bar adaptedto attach to two cephalad arms of the implanted spinal arthroplastydevice.

In embodiments in which the implanted spinal arthroplasty device has acephalad arm, the revision device may also include a new cephalad armand an attachment mechanism adapted to attach the new cephalad arm to aremaining portion of the implanted cephalad arm (medially or laterallyof the implanted cephalad arm) after a portion of the implanted cephaladarm has been removed. In such embodiments, the revision device may alsohave a connector housing attached to the new cephalad arm and beingadapted to attach to an other arthroplasty device element (such as thecaudal component) or revision device element. The revision device mayalso have a caudal attachment device adapted to be attached to a caudalcup fixation element after the caudal cup has been removed, theconnector housing being adapted to be attached to the caudal attachmentdevice. In embodiments in which the implanted spinal arthroplasty devicehas two cephalad arms, the revision device may have two new cephaladarms, each having an attachment mechanism adapted to attach one of thenew cephalad arms to a remaining portion of a respective implantedcephalad arm after a portion of such implanted cephalad arm has beenremoved.

Still another aspect of the invention provides a revision device for animplanted spinal device (such as, e.g., a spinal arthroplasty device, afacet joint replacement device, a dynamic stabilization device, ininterspinous space, and/or an artificial disc), where the implantedspinal arthroplasty device has a cephalad component fixed to a firstvertebra and a caudal component fixed to a second vertebra inferior tothe first vertebra, the cephalad and caudal components having abiomechanical relationship (such as, e.g., a range of motion) betweenthem. The revision device according to this aspect of the inventionincludes a first surface adapted to interact with the cephalad componentand a second surface adapted to interact with the caudal component toalter the biomechanical relationship (e.g., to limit motion) between thecephalad and caudal components. In some embodiments in which thecephalad component of the implanted spinal device has a cephalad bearingelement and the caudal component has a caudal bearing element, therevision device is adapted to attach to the cephalad component on oneside of the cephalad bearing element and to attach to the caudalcomponent on a side of the caudal bearing element opposite to said oneside to, e.g., limit or eliminate motion between the cephalad and caudalcomponents. In embodiments in which the cephalad component also has acephalad arm, the revision device may include an attachment mechanismadapted to attach to the cephalad arm.

Various other alternative aspects of the invention provide for the useof one or more revision devices for implanted spinal devices, such asspinal arthroplasty devices, motion limiting devices (such asintervertebral spacers, artificial ligaments and/or dynamicstabilization devices), devices promoting arthrodesis (rod and screwsystems, cables, fusion cages, etc.), and/or vertebral replacementdevices. The revision devices according to these aspects of theinvention may include a linkage or linkages that serves to augmentand/or replace a pre-existing connection between adjacent and/ornon-adjacent vertebral bodies. Such devices can increase, decreaseand/or alter the amount, range and/or quality of motion allowed orpermitted between the targeted vertebral bodies, depending upon thedesired surgical outcome, as well as the current condition and/or needsof the patient

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a perspective view of an implanted spinal arthroplasty device.

FIG. 2 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to on embodiment of theinvention.

FIG. 3 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to another embodiment of theinvention.

FIG. 4 shows details of one aspect of the embodiment of FIG. 3.

FIG. 5 shows details of an alternative connection mechanism to be usedwith the embodiment of FIG. 3.

FIG. 6 is an exploded view of yet another connection mechanism to beused with the embodiment of FIG. 3.

FIG. 7 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to yet another embodiment of theinvention.

FIG. 8 shows details of a crossbar of a revision device attached to twocephalad arms.

FIG. 9 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to yet another embodiment of theinvention.

FIG. 10 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to still another embodiment ofthe invention.

FIG. 11A illustrates a securing device for use in connection with anarthroplasty device to revise and/or modify, control, or limit motion ofthe arthroplasty device.

FIG. 11B is a top view of the securing device of FIG. 11A.

FIG. 11C is a side view of the securing device of FIG. 11A.

FIG. 11D is a bottom view of the securing device of FIG. 11A.

FIG. 11E is a cross-sectional view of the securing device of FIG. 11A.

FIG. 12A illustrates a side view of the securing device of FIG. 11 incombination with a portion of the arthroplasty device of FIG. 1.

FIG. 12B illustrates a perspective view of the securing device incombination with a portion of the arthroplasty device.

FIG. 12C is a perspective view from an anterior perspective of thesecuring device in combination with a portion of the arthroplastydevice.

FIG. 12D is a top view of the securing device with a portion of thearthroplasty device

FIG. 12E is a bottom view of the securing device with a portion of thearthroplasty device.

FIG. 13A is a perspective view of an implanted arthroplasty device withthe securing device of FIG. 11.

FIG. 13B is a perspective view of another implanted arthroplasty devicewith the securing device of FIG. 11.

FIG. 13C is a perspective view of yet another implanted arthroplastydevice with another embodiment of a securing device constructed inaccordance with the teachings of the present invention.

FIG. 14 shows an implanted spinal arthroplasty device that has beenrevised by a revision device according to another embodiment of theinvention.

FIG. 15 shows a top view of certain components of the revision deviceand implanted arthroplasty device of FIG. 14.

FIG. 16 shows a perspective view of certain components of the revisiondevice and implanted arthroplasty device of FIG. 14.

FIG. 17 shows a top view of certain components of an alternativerevision device and implanted arthroplasty device.

FIG. 18 shows a perspective view of the components of the revisiondevice and implanted arthroplasty device of FIG. 17.

FIG. 19 shows an implanted spinal arthroplasty device with attachmentholes for a revision device

DETAILED DESCRIPTION OF THE INVENTION

The revision devices and methods of this invention may be used with avariety of spinal implants, such as arthroplasty implants. FIG. 1 showsan exemplary spinal arthroplasty device attached to adjacent vertebrae14 and 14′. The spinal arthroplasty device includes a crossbar 105, apair of cephalad arms 120, 120′ and a pair of caudal cups 150, 150′.Heads 110 and 115 at opposing ends of crossbar 105 interact with bearingsurfaces inside caudal cups 150 and 150′ to replace the articulatingaction of the patient's natural facet joints, which have been removed,when the patient flexes and extends his or her back. In this example,each cephalad arm 120, 120′ attaches to the pedicle of the superiorvertebra 14 as shown, via, e.g., a stem (not shown) inserted into thepedicle. The other ends of the cephalad arms attach to crossbar 105 viacrossbar mounts 175 and 175′. The caudal cups 150 and 150′ attach to theinferior vertebra 14′ via, e.g., stems (not shown) inserted into thepedicles. Further details of this exemplary spinal arthroplasty devicemay be found in U.S. Ser. No. 11/206,676.

FIG. 2 shows an implanted spinal arthroplasty device that has beenrevised by a revision device. In this example, the revision devicealters the biomechanics of the implanted device by substantiallyeliminating movement between the cephalad and caudal members and,thereby, between the adjacent vertebrae. The caudal cups that had beenattached to inferior vertebra 14′ have been removed from their stems,which remain implanted. The caudal cups may be removed, e.g., bygrasping them with a grasping tool and/or through the application ofenergy (heat, vibration, ultrasound, etc.). In place of the caudal cups,attachment devices 180 and 180′ are attached to the exposed portions ofthe caudal stems. Caudal attachment devices, such as rods 182 and 182′,extend medially from attachment devices 180 and 180′. Alternatively, asingle rod extending between attachment devices 180 and 180′ may be usedin place of shorter rods 182 and 182′.

As shown in FIG. 2, instead of attaching to a movable crossbar, cephaladarms 120 and 120′ are now attached to the immovable caudal attachmentdevices via mounts 175 and 175′ or other connectors or housings.Addition of the revision device therefore substantially eliminatesmovement between the remaining cephalad and caudal components of theimplanted arthroplasty device and between vertebrae 14 and 14′. Acrossbar 184 may be added between the cephalad arms for additionalstability. The crossbar may have an adjustable length, as shown.Alternatively, the crossbar may have a fixed length and may possiblyprovide multiple cephalad arm attachment points selectable along itslength, as shown, e.g., in FIG. 7 or FIG. 8.

FIGS. 3 and 4 show a revision device according to another embodiment ofthe invention. As in the FIG. 2 embodiment, the caudal cups of theimplanted arthroplasty device have been removed and replaced withattachment devices 180 and 180′ attached to the implanted caudal stems165 and 165′. Caudal attachment rods 182 and 182′ extend from attachmentdevices 180 and 180′. In this embodiment, however, portions of thecephalad arms of the implanted arthroplasty device have been removed,e.g., to provide access to otherwise inaccessible portions of the spinalanatomy. Removal of such portions (or other components of thearthroplasty device) may be desirous to allow surgical access toselected anatomy (such as the intervertebral disk and/or other posterioranatomy for disc replacement and/or augmentation, and/or installation offusion cages), removal of damaged, dislodged and/or loose portions orcomponents, as well as those portions or components that may be causingundesirable anatomical effects (i.e., impinging upon nerves or otherstructures). The remaining portions 121 and 121′ of the cephalad armsprovide attachment points for the revision device. Specifically,cephalad attachment devices 190 and 190′ attach to the cephalad armportions by, e.g., set screws 191 and 191′. Two new cephalad arms 194and 194′ are attached to the cephalad attachment devices via attachmentmounts or housings 192 and 192′. The new cephalad arms 194 and 194′attach to the caudal attachment rods 182 and 182′ via mounts orconnector housings 196 and 196′. As in the FIG. 2 embodiment, therevision device shown in FIGS. 3 and 4 alters the biomechanics of theimplanted device by substantially eliminating movement between thecephalad and caudal members and, thereby, between the adjacentvertebrae. A crossbar (such as the crossbar shown in FIG. 2, 7 or 8) maybe attached to the new cephalad arms to provide additional stability forthe entire construct and/or for individual components relative to theconstruct (such as a loose cephalad arm).

FIGS. 5 and 6 show alternative connector housings for attaching the newcephalad arm to the remaining portion of the implanted cephalad arm. InFIG. 5, as in FIG. 3, the axis of the new cephalad arm is offset withrespect to the axis of the remaining portion 121′ of the implantedcephalad arm. In FIG. 6, the new cephalad arm 194′ is substantiallyuniaxial with the remaining portion 121′ of the implanted cephalad arm.

FIG. 7 is an embodiment similar to that of FIG. 2 and shows an implantedspinal arthroplasty device that has been revised by a revision device.As in the FIG. 2 embodiment, the revision device alters the biomechanicsof the implanted device by substantially eliminating movement betweenthe cephalad and caudal members and between the adjacent vertebrae. Thecaudal cups that had been attached to inferior vertebra 14′ have beenremoved from their stems, which remain implanted. In place of the caudalcups, attachment devices 180 and 180′ are attached to the exposedportions of the caudal sterns. Caudal attachment devices, such as rods182 and 182′, extend medially from attachment devices 180 and 180′.Cephalad arms 120 and 120′ are attached to the immovable caudalattachment rods via mounts 175 and 175′ or other connectors or housings.Addition of the revision device therefore substantially eliminatesmovement between the remaining cephalad and caudal components of theimplanted arthroplasty device and between vertebrae 14 and 14′. Crossbar184 has been added between the cephalad arms for additional stability.In this embodiment, the point at which crossbar 184 attaches to cephaladarm 120 may be adjusted through the interaction of attachment screw 188and crossbar slot 189.

FIG. 8 shows an alternative adjustable cephalad arm crossbar 184 for usein a spinal arthroplasty revision device. The effective length ofcrossbar 184 can be adjusted through the interaction of adjustment screw188 and crossbar slot 189.

FIG. 9 shows yet another embodiment of a revision device attached toremaining portions 121 and 121′ of removed cephalad arms of an implantedspinal arthroplasty device. As in other embodiments, the caudal cups ofthe implanted arthroplasty device have been removed and replaced withattachment devices 180 and 180′ attached to the implanted caudal stems,and caudal attachment rods 182 and 182′ extend from attachment devices180 and 180′. As in the FIG. 3 embodiment, portions of the cephalad armsof the implanted arthroplasty device have been removed, e.g., to provideaccess to otherwise inaccessible portions of the spinal anatomy, and theremaining portions 121 and 121′ of the cephalad arms provide attachmentpoints for the revision device. Cephalad attachment devices 190 and 190′attach to the cephalad arm portions by, e.g., set screws 191 and 191′.Two new cephalad arms 194 and 194′ are attached to the cephaladattachment devices via attachment mounts or housings 192 and 192′.Unlike the FIG. 3 embodiment in which the new cephalad arms are disposedlateral to the remaining portions of the implanted cephalad arms, inthis embodiment the new cephalad arms 194 and 194′ are medial to theremaining portions 121 and 121′ of the implanted cephalad arms. Also,the new cephalad arms 194 and 194′ attach to the caudal attachment rods182 and 182′ via mounts or connector housings 196 and 196′ at locationsmedial to caudal attachment devices 180 and 180′. A crossbar 184 isattached to the new cephalad arms to provide additional stability. Therevision device shown in FIG. 9 alters the biomechanics of the implanteddevice by substantially eliminating movement between the cephalad andcaudal members and, thereby, between the adjacent vertebrae.

FIG. 10 shows still another embodiment of a spinal arthroplasty revisiondevice (including cephalad attachment device 190′, new cephalad arm 194′and attachment housings 192′ and 196′) attached to only one side of thespine and lateral to both the implanted cephalad arm 121′ and the caudalattachment device 180′. The remaining portion 121 of the other implantedcephalad arm and the other caudal stem 165 are not being used as part ofthe revision (although such portions could be utilized for the revision,if desired, or as anchoring points for other spinal hardware). Use of alateral location for the revision device may be useful in cases wherethe patient's anatomy does not permit a medial position for the revisiondevice due, e.g., to the size of the patient or to the limited amount ofbone that had previously been removed and/or the location of the spinalcord/nerves and other anatomical structures.

FIG. 11A illustrates a revision or securing device for use in connectionwith an arthroplasty device to revise and/or modify, control, or limitmotion of the arthroplasty device. The securing device has a body 520with a distal surface 521 having pair of prongs 522, 522′. Wheninstalled, the prongs 522, 522′ form a base and are positioned below thecrossbar member and the indenture 524 of the securing device engages theanchors on three sides. When used with a device of FIG. 1, the prongscan be positioned below the caudal cup which receives an end of thecrossbar member, while the top sits above the crossbar end (110, 115) tosecure the end in place within the caudal cup 150.

The prongs 522, 522′ engage a wall 526 of the securing device on oneside. The wall 526 mates with a top or roof 528 that fits above thecross-bar member. The top 528 has an aperture 529. The aperture 529 canfunction as a detent, catch or plunger to snap fit over the ball end 110of the crossbar member in an arthroplasty device. Alternatively, thesecuring device can be a securing mechanism, such as a set screw 530.FIG. 11B is a top view of the securing device 520. From thisperspective, it is apparent that the top 528 can be positioned off acentral axis of the device to the two prongs 522, 522′, thus alsopotentially positioning the aperture 529 off the central axis as well.FIG. 11C is a side view of the securing device, illustrating the angledconfigurations of the sides 531, 531′ back wall 526. The angledconfiguration positions the top 528, which can have a smaller dimensionin at least one direction (e.g., length or width) than the length orwidth formed by the prongs and the wall. FIG. 11D is a bottom view ofthe securing device 520. FIG. 11E is a cross-sectional view of thesecuring device taken through an axis parallel to the prongs 522, 522′.

FIG. 12A illustrates a side view of the securing device of FIG. 11 incombination with a portion of an arthroplasty device, such as thearthroplasty device of FIG. 1. The prongs 522, 522′ sit below the caudalcup 150, holding the caudal cup in a fixed position. The top 528 of thesecuring device 520 sits above an end of the cross-member 110, whichfits within the caudal cup 150. An anchoring device 530 (see FIG. 11A)can be fed through the aperture to engage the end of the cross-memberand hold it in position within the caudal cup 150. As illustrated, thecaudal cup 150 is tilted t toward an axial plane 52, enabling the caudalcup to secure the cross-member at a location. Adjustment of the positionof the caudal cup relative to the cross-member end can affect theposition of the device. FIG. 12B illustrates a perspective view of thesecuring device in combination with a portion of the arthroplastydevice. From this perspective, a set screw 530 located within theaperture 529 on the top of the securing device can be seen. FIG. 12C isa perspective view from a partially anterior view of the securing deviceagain in combination with a portion of the arthroplasty device. FIG. 12Dis a top view of the securing device 520 with a portion of thearthroplasty device. As evident from this perspective, the caudal cupextends on one side past the prong 522′. The set screw 530 is positionedoff-center relative to the length of the securing device, but the top ofthe securing device is positioned over the end of the cross-member. FIG.12E is a bottom view of the securing device engaging an arthroplastydevice. From this view, it is illustrated that the prongs 522, 522′ areseated beneath, for example, the caudal cup of the arthroplasty device.

Thus, the implanted arthroplasty device can be revised to incorporatelocks or “fusion caps” that desirably convert the device from anarticulating joint replacement construct to a non-articulating (orcontrolled and/or limited articulation) spinal fusion construct. In thisembodiment, the fusion cap can be installed on or into the caudal cupsto desirably immobilize the cephalad bearings within the cups. Invarious embodiments, the fusion caps could immobilize the cephaladbearings by direct compression or contact, through use of a set screw orother device to secure the cephalad bearing relative to the cup, or thefusion cap could contain or cover an encapsulating material, such asbone cement, which could fill the caudal cup and immobilize the cephaladbearing. Various techniques could be used in conjunction with theinstallation of such fusion caps, and the cap could be installed priorto, during, or after the completion of a concurrent spinal fusionprocedure, including the removal of intervertebral disc material,installation of fusion cages, and/or introduction of material (such asbone graft material) that desirably promotes spinal fusion. If desired,the bearing surface could be textured and/or knurled to increasefriction between the ball, bearing surface and/or the fusion construct.Alternative embodiments could incorporate bearings of different shapesor sizes (not shown), including square or non-spherical bearings and/orbearings shaped to that fit snugly into and accommodate most or all ofthe interior of the caudal cup (not shown), that can be secured withinthe cup in a similar manner.

Turning now to FIG. 13A, a perspective view of an implanted arthroplastydevice 600 with the securing device of FIG. 11 is illustrated. Thearthroplasty device 600 features a pair of caudal cups 150 engaging across-member 110. The cephalad arms have been removed, but it has beendetermined desirable to keep the caudal cups and cross-bar in place. Theuse of the securing device enables the caudal cup and crossbar member tobe retained in position even without one or more of the cephalad arms toanchor the cross-member. Additionally, as will be appreciated by thoseof skill in the art, one of the two cephalad arms could be removed withthe use of one or two of the securing devices to provide a three-pointsecured device (i.e., rigidly connecting two caudal cups to a singlecephalad arm). The securing device engages the caudal cup and an end ofthe cross-member in the manner described above. FIG. 13B is aperspective view of another implanted spinal arthroplasty device 602having a pair of caudal cups 150, 150′ engaging a cross-member 110 and apair of cephalad arms 120, 120′ extending vertically toward the adjacentvertebra 12 along with the securing device of FIG. 11. FIG. 13C is aperspective view of yet another implanted arthroplasty device 604 withthe securing device of FIG. 11.

FIGS. 14-18 show still other embodiments of a spinal arthroplastyrevision system according to the invention. FIGS. 14-16 show animplanted spinal arthroplasty system (such as that shown in FIG. 1) withcephalad arms 120 and 120′, cephalad heads (such as head 110 shown inFIG. 16) at either end of a cephalad crossbar 105 and caudal cups 150and 150′. The cephalad arms connect to crossbar 105 via crossbar mounts175 and 175′. Revision devices 200 and 200′ have been added to theimplanted arthroplasty prosthesis to substantially eliminate movementbetween the cephalad heads and the caudal cups and, thereby, betweenadjacent vertebrae 14 and 14′. As shown in detail in FIGS. 15 and 16,the revision device includes a securing section 202′ similar to that ofFIG. 11 extending from one side of the caudal cup 150′ to an opposingside of the cephalad head 110. Securing sections 202 and 202′ lock thecephalad heads against the caudal cups with screws and 203 and 203′.Cephalad arm hook plates and connectors 204 and 204′ are attached to thesecuring section 202′ (via screw 203 or 203′) and to cephalad arms 120and 120′ (via set screw 205 or 205′) to provide additional stability.The upper surfaces of the securing sections 202 and 202's and the lowersurfaces of hook plates 204 and 204′ may have complementary shapes(e.g., spherical) and roughened surface texture to form a more secureconnection between them. Revision devices 200 and 200′ alter thebiomechanics of the implanted device by substantially eliminatingmovement between the cephalad and caudal members and between theadjacent vertebrae, thereby transforming the implanted spinalarthroplasty device into a fusion device.

FIGS. 17 and 18 show an alternative design to the revision devices 200or 200′ of FIGS. 14-16. 100671 The first step of adding a revisionsystem, such as one of those shown above in FIGS. 14-18, to an implantedspinal arthroplasty device, is to expose the existing device. Boneand/or soft tissue may be removed from under the caudal cup to make roomfor the securing device, such as securing device 202 or 202′ in FIGS.14-18. After placing the securing devices 202 and 202′ around caudalcups 150 and 150′ and the cephalad heads at either end of crossbar 105,screws 203 and 203′ are tightened (to, e.g., 70 in-lbf) to hold thecephalad and caudal components together. The cephalad heads arepreferably in the “home” position within their respective caudal cups.The vertebrae can be compressed prior to final assembly of the revisiondevice, if desired. A hook plate of suitable size and dimensions isselected (from, e.g., a kit containing multiple hook plates of varioussizes) and placed over a portion of the securing device screw 203 or203′ extending above the securing device 202 or 202′. The hook plate isattached to its corresponding cephalad arm via set screw 205 or 205′.Bone graft material may be added to facilitate fusion. The incision maythen be irrigated and closed in a standard fashion.

The revision devices of this invention may be provided in kitscontaining components of various sizes so that the revision device canbe tailored to the patient's anatomy. In addition, the kits may containthe removal, sizing and implantation tools needed to perform therevision procedure.

FIG. 19 shows an implanted spinal arthroplasty device similar to thatshown in FIG. 1. As in the FIG. 1 embodiment, cephalad arms 120 and 120′connect via crossbar mounts 175 and 175′ to a cephalad crossbar 105having heads 110 and 115 at either end. In this device, however, thecaudal cups 150 and 150′ are connected with a crossbar 212 as well. Inaddition, cephalad crossbar 105 has an opening 210 that lines up with anopening (not shown) in caudal crossbar 212. The two openings may be usedto secure a revision device, e.g., to secure the cephalad and caudalcomponents together during installation or to limit or eliminate therange of motion between the cephalad and caudal components.

While the various embodiments of the invention have been described inthe context of a spinal arthroplasty device revision that substantiallyeliminates motion between the cephalad and caudal device components(i.e., fusion), it should be understood that the revision device mayalter but still permit motion between the cephalad and caudalcomponents.

What is claimed is:
 1. A system for implantation comprising: a firstcaudal cup; a second caudal cup; a crossbar member extending between thefirst caudal cup and the second caudal cup, wherein the crossbar memberhas a first end that engages the first caudal cup and a second end thatengages the second caudal cup; and a securing device for limiting motionof the system, the securing device including a lower portion thatengages the first caudal cup and an upper portion that engages the firstend of the crossbar member.
 2. The system of claim 1, wherein the firstend of the crossbar member comprises a head member.
 3. The system ofclaim 1, wherein the lower portion of the securing device comprises afirst prong and a second prong.
 4. The system of claim 3, wherein thefirst prong and the second prong are positioned below the first caudalcup.
 5. The system of claim 1, wherein the upper portion of the securingdevice comprises a roof with an aperture therethrough.
 6. The system ofclaim 5, wherein the roof receives a set screw that engages the firstend of the crossbar member.
 7. The system of claim 1, wherein the lowerportion of the securing device comprises a first prong and a secondprong and the upper portion of the securing device comprises a roofhaving a set screw received therein, wherein the set screw is off-centerrelative to an overall length of the securing device.
 8. The system ofclaim 1, wherein the securing device comprises a three-point securingdevice around the first caudal cup and the crossbar member.
 9. A systemfor implantation comprising: a first caudal cup; a second caudal cup; acrossbar member extending between the first caudal cup and the secondcaudal cup, wherein the crossbar member has a first end that engages thefirst caudal cup and a second end that engages the second caudal cup;and a securing device for limiting motion of the system, wherein thesecuring device comprises a three-point securing device around the firstcaudal cup and the crossbar member.
 10. The system of claim 9, whereinthe securing device comprises a first prong and a second prong.
 11. Thesystem of claim 10, wherein the securing device further comprises aroof.
 12. The system of claim 11, wherein the roof comprises an aperturetherein.
 13. The system of claim 12, wherein the roof receives a setscrew through the aperture.
 14. The system of claim 13, wherein the setscrew engages the crossbar member and the first prong and the secondprong engage the first caudal cup.
 15. The system of claim 13, whereinthe set screw is off-center from a central axis of the securing device.16. The system of claim 9, wherein the first end and the second end ofthe crossbar member comprise rounded ends.
 17. A securing device forimplantation, comprising: an upper portion comprising a roof; a lowerportion comprising a first prong and a second prong; and a surfaceextending between the upper portion and the lower portion, wherein theroof is offset from a central line that extends between the first prongand the second prong.
 18. The securing device of claim 17, wherein theroof comprises an aperture extending therethrough.
 19. The securingdevice of claim 18, further comprising a set screw received in theaperture.
 20. The securing device of claim 19, wherein the set screw isthreaded.